This invention relates to a method of rolling a strip, especially a metal strip.
A known apparatus for practicing the method of this character is that made public by Japanese Patent Application Disclosure No. 25043/1972. As described in the specification of the cited application, we previously proposed a tensioning-bending strip rolling apparatus which, when rolling and flattering a strip by a set of small and large work rolls while giving it a predetermined tension or velocity difference by means of bridle rolls, bends the strip toward or around the small work roll, whereby a high draft is attained. The rolled product is satisfactorily controlled in shape, and, moreover, the apparatus is made compact in construction.
Our further intensive stuides and experiments have revealed that the bending of the strip around the small work roll is not essential, if the diameter ratio of the small and large work rolls is fixed within a certain range, if at least one of the small and large work rolls in a set or of the rolls in a group backing up the work rolls is driven, and if the strip is rolled while being bent to a suitable angle, or entry-exit angle. It has thus been found that, even when rolling a strip to a very thin sheet less than 0.2 mm in thickness, the tension control of the strip is easy and a good rolling result can be obtained.
As other approaches, apparatuses have already been proposed, including those taught by Japanese Patent Application Disclosure Nos. 5848/1979 and 10259/1979, for example, whereby a strip is rolled while being efficiently wound round a pair of work rolls. Those apparatuses have drawbacks however in that the pair of work rolls, with the same diameter, cannot fully achieve the effect of beinding a strip by applying a rolling pressure on the outer side of the curved workpiece, and therefore the rolling force required is great and a very thin sheet cannot be obtained by high-draft rolling. Furthermore, the apparatuses are inevitably large in size.